Method of making rupturable containers



Aug. 8, 1967 v. J. DE SANTIS 3,3 0

METHOD OF MAKING RUPTURABLE CONTAINERS Original Filed July r, 1961- 2 Sheets-Sheet 1 IN'VENTOR: VINCENT J. DESANTIS,

HIS TTORNEY.

Aug. 8, 1967 v. J. DE smms METHOD OF MAKING RUPTURABLE CONTAINERS 2 Sheets-Sheet 2 Original Filed July 7, 1961 FIG.6.

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I NVE NTO R VINCENT J. DE SANT'IS WWW H I S ATTORN EY.

United States Patent 3,334,407 METHOD OF MAKING RUPTURABLE CONTAINERS Vincent J. De Santis, Schenectady, N.Y., assignor to General Electric Company, a corporation of New York Original application July 7, 1961, Ser. No. 122,487, now Patent No. 3,300,037, dated Jan. 24, 1967. Divided and this application Aug. 11, 1966, Ser. No. 596,356

5 Claims. (Cl. 29-412) This application is a division of applicants copending application Ser. No. 122,487, filed July 7, 1961, now Patent No. 3,300,037, granted Jan. 24, 1967, and assigned to the same assignee as the present invention. The present invention relates to sealed containers of the type filled with a substance which subsequently may be liberated into the circumambient environment which itself may -be a hermetically sealed container, such as the envelope of an electron discharge device or the like. More particularly, the present invention relates to new and improved rupturable containers and new and improved methods of manufacturing same.

In a variety of technological applications, it is often necessary to fill a hollow, evacuated, hermetically sealed structure with a particular fluid after that structure has been evacuated and sealed. The manufacture of certain electron discharge devices exemplifies one such application. A method currently employed in the production of thyratrons, for instance, requires that the mercury which provides the necessary vapor be introduced into the assembled thyratron after that device has been exhausted and hermetically sealed.

A variety of methods have heretofore been suggested and have been devised to effect filling of electron discharge devices with a vapor following evacuation and seal off. One method currently employed involves the use of a sealed glass capsule containing a required quantity of an inert gas or of a metal whose vapor is to fill the device. The glass capsule is encased in a perforated metal container adapted for being heated by induction heating techniques. The encased capsule is assembled in the envelope of the electron discharge device and, following exhaust and seal off of the envelope, the capsule containing the substance to be liberated is rapidly brought to a temperature at which the glass either fractures, or is softened to a viscosity which is sufiiciently low, so as to permit the encapsulated substance to rupture the capsule and thus be released into the circumambient environment.

However, such a method is often inimical to the successful operation of the filled electron discharge device. The damage occurring as a result of utilizing such a method is attributed primarily to the evolution of objectionable gases from the ruptured glass capsule. Additionally, small particles of the glass capsule are free to migrate into regions of the electron device where their presence can cause malfunctioning of the device.

It is, therefore, desirable to provide structure which does not involve the use of a glass capsule, is adapted for quickly and easily releasing the contained substance and which is effective for avoiding introduction of undesirable gases. Additionally, it is desirable to provide means for effectively sorbing any undesired gases that may be present in the container into which the vapor is to be released.

Accordingly, it is the primary object of the present invention to provide a new and improved hermetically sealed container of the type filled with a substance which may be easily liberated into the circumambient environment.

Another object of the present invention is to provide a new and improved hermetically sealed container including a portion which is relatively weaker than the remaining portion and, thus, more susceptible to rupture upon heating, thereby to release a contained substance.

Another object of the present invention is to provide a new and improved hermetically sealed container at least a portion of which comprises at least two metals to form an alloy having a melting point below the melting point of any one of the alloy constituents.

A further object of the present invention is to provide a new and improved hermetically sealed capsule at least a portion of which comprises at least two metals to provide a eutectic alloy.

Another object of the present invention is to provide a new and improved hermetically sealed capsule having a portion which is more fusible than the remainder of the capsule and thereby is adapted to facilitate the loading of electron discharge devices of the type employing a gaseous atmosphere.

Another object of the present invention is to provide a new and improved hermetically sealed metallic capsule at least a portion of which comprises two metals to form an alloy having a melting point lower than the melting point of any constituent thereof, at least one constituent of which alloy comprises a getter material.

Another object of the present invention is to provide a new and improved article of manufacture adapted for use as both a getter element and means for releasing a fluid substance into the circumambient atmosphere.

Another object of the present invention is to provide a new and improved method of manufacturing capsules for use in charging containers with a fluid substance.

Another object of the present invention is to provide new and improved means for manufacturing electron discharge devices of the type employing a gaseous atmosphere including new and improved means and methods for loading such devices with the desired gaseous atmosphere.

Still other objects and advantages of the present invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In carrying out the objects of the invention there is provided an article of manufacture in the form of a hermetically sealed metal capsule containing a substance, such, for example, as mercury, to be released therefrom and into a circumambient atmosphere. The capsule includes a discrete wall section which is more readily rupturable than the remainder of the capsule upon heating and resultant thermal expansion of the contents of the capsule. The mentioned discrete more readily rupturable section can comprise a relatively thinner, and thus weaker section. Alternatively, the mentioned discrete section of the capsule can comprise a section formed of an alloy having a lower melting point, and thus being more readily fusible and rupturable, than the remainder of the capsule. In both mentioned forms the capsule can comprise a getter material whereby it can serve further as a getter element for sorbing undesired gases from its contents and the circumambient atmosphere into which it is to release its contents.

The mentioned article of manufacture can be constructed by first filling an elongated tube of getter material with a fluid substance, hermetically sealing the ends of the tube, and subdividing the tube into a plurality of discrete hermetically sealed capsules of predetermined volume. Additionally, during this encapsulating process the tube can be heated for rendering the gettering material thereof effective for sorbing undesired gases from the contents of the tube. The mentioned more readily fusible wall section can be provided by providing on an exterior surface of the capsule a quantity of a metal which will upon heating alloy with the metal of which the capsule is formed and thereby form the section having a lower melting point. Alternatively, the metal provided for alloying with the capsule metal can be positioned in the welded joints of the capsule wall as by positioning an elongated strip thereof in the elongated tube before subdivision thereof into discrete capsules. In the manufacture of an electric discharge device a capsule manufactured according to the invention can be appropriately mounted in the envelope of the device. The capsule can be inductively heated which will render the getter material therein effective for sorbing undesired gases. Additionally, the heating will serve to rupture the capsule and release its contents. The rupturing can result through weakening of the capsule wall by reducing the thickness of a portion thereof or by providing the wall with a more fusible and thus more readily rupturable section.

For a better understanding of the invention reference may be had to the accompanying drawing wherein:

FIGURE 1 is an enlarged perspective view showing a hermetically sealed capsule embodying one form of the present invention;

FIGURE 2 is an enlarged fragmentary sectional view of the hermetically sealed capsule shown in FIGURE 1;

FIGURES 3 and 4 illustrate a method of manufacturing the capsule of FIGURES 1 and 2;

FIGURE 5 is an enlarged perspective view of a capsule constructed according to a modified form of the invention;

FIGURES 6 and 7 illustrate means employable in manufacturing capsules of the type shown in FIGURE 5;

FIGURE 8 is a fragmentary sectional view of a hermetically sealed capsule constructed according to still another embodiment of the invention;

FIGURE 9 is an enlarged fragmentary elevational view, partly in section, of one form of an electron discharge device in the construction of which the new and improved hermetically sealed body of the present invention is particularly applicable, and

FIGURE 10 is a side elevational view of the electron discharge device shown in FIGURE 9.

Referring to the drawing, there is illustrated in FIG- URE 1 a hermetically sealed capsule 10 constructed in accordance with one form of the invention and including a thin-walled metallic tubular section 11 having its end portions 12 compressed and hermetically sealed in accordance with any of the well-known sealing techniques, such, for example, as cold welding. Prior to sealing, the capsule 10 is filled with a substance such as mercury, for example, which is subsequently to be used to fill an electron discharge device such as a thyratron with mercury vapor. Secured to the outer surface of the capsule, as by spot welding, is a tab of metal 13 adapted when heated to alloy with the metal of the capsule 10 and thus form a discrete section of the capsule which constitutes an alloy having a melting point considerably lower than the melting point of the metal constituting the metallic tubular section 11. When properly installed in an electric discharge device, and subjected to an appropriate elevated temperature, the alloy formed by the tab 13 and the material of the tubular section 11 is more readily fusible than the remainder of the capsule and thus facilitates rupturing the tubular section 11 whereby the substance contained Within the capsule 10 is permitted to escape into the circumambient environment.

Illustrated in FIGURES 3 and 4 are means and method for fabricating the capsule 10. As illustrated in FIG- URE 3, a plurality of capsules can be formed from a single elongated tubular section. The elongated tubular section is first filled with the fluid to be contained in the individual capsules and then the ends are sealed as by cold welding in the manner shown in FIGURE 3. Then, according to the volume of material desired to be contained in each capsule and as seen in FIGURE 4, the individual capsules are formed by compressing the elongated tubular section 15 at predetermined spaced points along the length thereof, thereby to effect seals, as by cold welding, between the individual segments. Additionally, at the seals, the segments are severed as by means of a shearing device 16. Either prior to or after the individual capsules are thus formed, the tab 13 can be secured to the exterior surfaces of the tubular sections 11. Further, an induction heating coil A can be used to heat the tubular section 15 to sor-b undesired gases contained therein and to alloy the materials of which the tubular section 15 and tabs 13 are formed.

The capsule 10 can serve effectively for both introducing a fluid substance into an envelope in the manner above described and as a gettering device. When serving both purposes, the material of which the tubular section 11 is formed can advantageously constitute titanium, hafnium, zirconium, tatalum or any other gettering material of which a tubular section can be formed. Additionally, when such materials are employed the tab 13 can advantageously comprise copper, iron, nickel or alloys or combinations of these materials. Thus, the tab 13 will constitute a material which will readily alloy with the material of which the tubular section 11 is formed, thereby to provide a section of the capsule which is more readily rupturable upon heating than the remaining section of the capsule.

Illustrated in FIGURE 5 is a modified form of the invention designated 20. The capsule 20 can be identical to the capsule 10 except that the element designated 21 constitutes the material adapted for alloying with the material of which the tubular section of the capsule is formed. The capsule 20 includes a section preferably formed of the above-mentioned gettering materials, titanium, hafnium, zirconium, tantalum and combinations thereof and the element 21 constitutes a strip of material selected from the group consisting of copper, iron, nickel, and combinations thereof which, as indicated above, will alloy readily upon heating with the material of which the tubular section of the capsule is formed. In this embodiment instead of having the alloying material secured to the outer surface of the capsule it is sealed in the capsule along the longitudinal axis thereof. Thus, it is present at the sealed end portions 21 for alloying with the capsule body material and thereby providing a more readily rupturable section of the device.

Illustrated in FIGURES 6 and 7 is means whereby a plurality of the capsules 20 of FIGURE 5 can be formed from an elongated tubular section. In a manner similar to that discussed above with respect to FIGURES 3 and 4, an elongated tubular section 22 can be formed, filled with a fluid substance and sealed at the ends in the manner shown in FIGURES 6 and 7. Additionally, an elongated strip 23 of material selected from the group consisting of copper, iron, nickel and combinations thereof is sealed in a longitudinally extending position in the tubular section 22. Thereafter, and according to the volume of material to be contained in each individual capsule, the elongated tubular section 22 is subdivided as by compressing between desired lengths thereof and severing in the manner illustrated in FIGURE 4. As also illustrated in FIGURE 4, means such as an inductive heating coil A can be employed for heating the tubular section such that the gettering material of which the tubular section is formed is effective for purifying or degassing the material contained in the tubular section and to alloy the materials adapted to provide the more readily fusible sections.

Illustrated in FIGURE 8 is a modified form of the invention designated 25 and comprising a capsule including a tubular section 26 containing a fluid substance and including a wall section 27 which is relatively thin compared With the remaining wall sections of the capsule. Thus, the section 27 is relatively weaker than the remaining section and is more readily rupturable upon heating and expansion of the contents of the capsule 25. In this form of the invention also the. tubular section 26 can be formed of a gettering material selected from the group including titanium, hafnium, zirconium and tantalum and combinations thereof.

Illustrated in FIGURES 9 and 10 is an electron discharge device generally designated 30 which constitutes a form of device in the manufacture of which the present invention has particular utility. As shown in FIGURES 9 and 10 the electron discharge device can comprise a hermetically sealed envelope 31 formed of glass or any other suitable material and provided with a base 32 and including means for supporting structure generally designated 33 and including a plurality of cooperating electrode elements not shown. In order to fill the envelope 31 with an atmosphere of an inert gas or of a metallic vapor, the device 30 is provided with a sealed capsule 10 of the type illustrated in FIGURE 1. From the outset, however, it is to be understood that in the device 31 any one of the forms of the above-described capsules is equally suitably employable.

The capsule 10 is suspended from the electrode supporting structure 33 by means of metallic leads 34 which can be attached to the capsule 10 in any suitable manner so as to provide support thereof. After the capsule 10 has been assembled in the device and the device has been exhausted and sealed, the capsule is rapidly brought to a temperature, as by inductive heating, at which the readily rupturable section formed by an alloy or a weakened section in the capsule will rupture so as to permit the substance contained therein to be discharged into the volume contained by the envelope 31.

As discussed above, the capsules are preferably formed of a getter or gettering material which when heated will sorb certain gases, Thus, the capsule 10 is eifective for both releasing a desired quantity of vapor into the envelope 31 and for being heated inductively to sorb any of the mentioned gases contained in the envelope.

It is to be understood from the foregoing that although the new and improved hermetically sealed capsules of the present invention have particular utility in the filling of electron discharge devices with desired atmospheres, the capsules may be used in a variety of applications requiring the discharge of a substance into the circumambient environment at a predetermined high temperature. Accordingly, it is emphasized that the present invention is not to be considered limited to any of the specific embodiments herein described but may be used in other ways without departure from the spirit of the invention and the scope of the appended claims.

What is claimed as new and described to be secured by Letters Patent of the United States is:

1. A method of manufacturing a capsule for releasing a fluid into a circumambient environment comprising the steps of filling an elongated metal tube with a fluid, sealing the ends of the tube, compressing intermediate sections of said tube to subdivide same intoa plurality of individual capsule sections of predetermined volume, sealing and severing said tube between said capsule sections and providing each of said capsules with a wall section which is more readily rupturable upon heating than the remainder.

2. A method of manufacturing a capsule for releasing a fluid into a circumambient environment comprising the steps of filling an elongated metal tube with a fluid, sealing the ends of the tube, compressing intermediate sections of said tube to subdivide same into a plurality of individual capsule sections of predetermined volume, sealing and severing said tube between said capsule sections, and afiixing to the wall section of each of said capsules a quantity of material which will alloy with the capsule material upon heating to provide a wall section which is more readily fusible than the remainder of said capsule.

3. A method of manufacturing a capsule for releasing a fluid into a circumambient environment comprising the steps of filling an elongated metal tube with a fluid, sealed from the ends of the tube, compressing intermediate sections of said tube to subdivide same into a plurality of individual capsule sections of predetermined volume, sealing and severing said tube between said capsule sections, and reducing the thickness of discrete wall portions of each of said capsules thereby to provide a Wall section which is more readily rupturable upon heating than the remainder of the capsule.

4. A method of manufacturing a capsule for releasing a fluid into a circumambient environment comprising the steps of positioning in said capsule a strip of material extending the length of said tube and which will alloy with the tube material upon heating to form an alloy which is more readily fusible than the material of which the tube is formed, filling said tube with a fluid, sealing the ends of said tube, compressing intermediate sections of said tube to subdivide same into a plurality of individual capsule sections of predetermined volume, and sealing and severing said tube between said capsule sections.

5. A method of manufacturing a capsule for releasing a fluid into a circumambient environment comprising the steps of filling an elongated metal tube formed of a gettering material with a fluid, heating said tube to elfect sorption of undesired gases from the contents thereof, compressing the intermediate sections of said tube to subdivide same into a plurality of individual capsule sections of predetermined volume, and sealing and severing said tube between said capsule sections.

References Cited UNITED STATES PATENTS 2,386,246 10/1945 Mapes 29-414 2,427,597 9/1947 Garner et al. 29-470.1 2,430,995 11/1947 Roos 29422 2,469,975 5/ 1949 McCloy 29-422 2,815,150 12/1957 Herzig 29413 JOHN F. CAMPBELL, Primary Examiner. THOMAS H. EAGER, Examiner, 

1. A METHOD OF MANUFACTURING A CAPSULE FOR RELEASING A FLUID INTO A CIRCUMAMBIENT ENVIROMENT COMPRISING THE STEPS OF FILLING AN ELONGATED METAL TUBE WITH A FLUID, SEALING THE ENDS OF THE TUBE, COMPRESSING INTERMEDIATE SECTIONS OF SAID TUBE TO SUBDIVIDE SAME INTO A PLURALITY OF INDIVIDUAL CAPSULE SECTIONS OF PREDETERMINED VOLUME, SEALING AND SEVERING SAID TUBE BETWEEN SAID CAPSULE SECTIONS AND PROVIDING EACH OF SAID CAPSULES WITH A WALL SECTION WHICH IS MORE READILY RUPTURABLE UPON HEATING THAN THE REMAINDER. 